Abstract

We report on a Cs-free GaNphotocathode structure in which band engineering at the photocathodesurface caused by Si delta doping eliminates the need for use of cesium for photocathode activation. The structure is capped with a highly doped layer. We have identified that cap thickness plays an important role in limiting the effect of polarization induced charges at the GaNsurface on the photocathode emission threshold. Physics based device simulations is used for further analysis of the experimental results. Our findings clearly illustrate the impact of polarization induced surfacecharges on the device properties including its emission threshold.

Received 27 April 2010Accepted 13 July 2010Published online 06 August 2010

Acknowledgments:

The research described in this paper was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under a contract (JPL46415) with National Aeronautics and Space Administration.